Low power heating element



Dec. 26, 1939. g -r 2,184,485

LOW POWER HEATING ELEMENT Filed March 29, 1937 semi. n... as, 1939 LOW POWER HEATING ELEMENT Etienne Challet, Paris, France, assignor of onefourth to Entreprises Electriques Fribourgeoises, llhrlibourg, Switzerland, as company of Switzer- Application March 29, 1937, Serial No. 133,710

In Switzerland April 6, 1936 6 Claims.

The present invention has for its object a low power electric heating element, characterized by the fact that the electric heating resistance is completely embedded and held against displacement in an insulating cushion formed of glass wool or of slag wool.

'The nature of the invention is clearly set forth in the drawing, of which Fig. 1 represents the heating element in cross section; 4

Figs. 2, 3 and 4 show the same heating element in cross section during various images of its manufacture.

In Fig. 1 a heating element according to the invention is seen in section. The heating resistance l in the shape of a coil is completely embedded in a cushion 2 made of glass wool or slag wool.

A heating element of this kind can be used in a number of low power apparatus: heating cushions or mats, heating panels or plates, etc. It has the advantage of being simple and perfectly insulated.

The invention further relates to a method of manufacturing the said heating element, which method is carried out in the following manner:

On a layer of glass woo or slag wool are placed the convolutions 4 of the resistance and an insulating plate 5 is placed over it, as seen in Fig. 2.

The whole arrangement is placed in a press jig (Fig. 3) shown in this case by two plates and I, which can be moved towards each other by means of nut which screw on screwed rods. After suitably clamping, a much stronger current is passed than that used in the normal service of the future heating element, in order to heat the. wire to incandescence. The heat emanating from the wire fuses the glass wool or slag wool immediately adjacent to the wire. After cooling this fused glass wool or slag wool solidifies into a thin layer which adapts itself exactly to the shape of the heating ofthe wire and at the same time is fused to the fibers of the glass wool or slag wool, which results in an elastic but comparatively firm connection between the cashion and the wire, and the element does not lose its elasticity on account of the spacing of the wire convolutions. The current is out off, the heating element is made and it then sumces to remove-the pressing apparatus toenable said element to be mounted in an apparatus in which it is to be used. v

I claim:

1. An electric heating element, comprising a fist, flexible cushion made of an electrically in-- misting-fusible material in fibrous state. an'elcctric resistance embedded immediately belowthe upper surface of said cushion, and a non-fibrous layer of said fusible material coating a substantial portion of said resistance, said layer being fused to said fusible material in fibrous state.

2. An electric heating element, comprising a flat flexible cushion made of glass wool, 'and an electric resistance embedded immediately below the upper surface of said cushion, and a layer of non-fibrous glass coating a substantial portion of said resistance, said layer being fused to said glass wool.

3. An electric heating element, comprising a flat flexible cushion made of slag wool, and an electric resistance embedded immediately below the upper surface of said cushion, and a layer of non-fibrous slag costing a substantial portion of said resistance, said layer being fused to said slag wool.

4. The method of manufacturing a flexible go electric heating element, which comprises placinga resistance coil on a flexible cushion made or an electrically insulating fusible material in fibrous state, pressing the coil against the cushion, passing a strong current through the wire of the coil to heat said coilv to incandescence,

thereby softening the insulating cushion, continuing the pressure until the coil'becomes embedded in said cushion, and cutting said current after said coil has become embedded in said material and before the material not immediately adjacent to said coil has fused.

5. The method of manufacturing a flexible electric heating element, which comprises placing a resistance coil on a flexible cushion made as of glass wool, pressing the coil against the cushion, passing a strong current through the wire of the coil to heat said, coil to incandescence, thereby softeningthe insulating cushion, continuing the pressure until the coilbecomes emw bedded in said cushion, and cutting off said current after said coil has become embedded in said glass wool and before the glass wool not immediately adjacent to said coil has fused.

6. The method of manufacturing a flexible a electric heating element, which comprises placing a resistance coil on 'a' flexible cushion made of slag wool, "pressing the coil against the cushion, passing a strong current through the wire of the coil to heat said coil to incandescence thereby softening the insulating cushion, continuing the pressure until the coil becomes embedded in said cushion and cutting off said ourrentafter said coil has become embedded in said slag wool and before the slag wool' not immedi 5 ately adiacenttosaidcoilhasfuscd.

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